Since September 1917 German bomber aviation had revised its plan of air campaign against the British Isles: after eight daylight raids the losses of important strategic bombers were too high, therefore, the decision was made to conduct all forthcoming raids only at night. At that point the newly created British Home Defence did not have a dedicated type of fighter interceptor. The majority of planes serving in Home Defence were fighters retired from the front line - a few two-seater Sopwith 1½ Strutter fighters among them.